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The Barnet Book of Photography A Collection of Practical Articles

If the frilling spreads rapidly


FRILLING.--It

sometimes happens that during the various operations of development, fixing and washing, the film begins to leave the plate and rise in puckers along the edges. This is known as "frilling," and in bad cases it may spread until a large part of the film has detached itself from the glass. It is due to excessive or irregular absorption of water by the gelatine, and at one time was commonly met with, but it rarely occurs with the dry plates of the present day. It is most likely to arise if there is any considerable difference of temperature between the various liquids and the wash-water, or during very hot weather when all the liquids are much warmer than usual.

When frilling does occur, the plate must be treated carefully, so as to avoid tearing the film, but unless it is very bad and shows a tendency to spread, all the operations, including washing after fixing, should be completed before any special measures are taken to remedy the defect. On the other hand, if the frilling spreads rapidly, the plate should be carefully rinsed two or three times with water and placed for five minutes in the alum bath, with occasional gentle rocking, after which it is again well washed to remove the alum, and the various operations are completed. There is one exception to the procedure just indicated; if the frilling becomes bad while the plate is being fixed or during washing after fixing, the alum must not be applied until the fixing and the washing after fixing

are completed. If something must be done in these circumstances, the plate, after draining, but without any previous washing, may be placed for about ten minutes in a saturated solution of common salt. It can afterwards be put back into the fixing bath, also without any intermediate washing, and the remainder of the process carried through.

Although the methods just described will check the frilling, they will not remove its effects. For this purpose the plate after its final washing is allowed to drain thoroughly and is then immersed in methylated alcohol, preferably of the old kind, though the new kind can be made to do. The alcohol abstracts water from the film, which consequently shrinks to its original size and can be pressed back with the fingers into its proper position on the plate. Should the film be opalescent it should be removed from the first quantity of alcohol and placed in a second quantity, after which it should be set up to dry. The plates should not remain too long in the alcohol or the gelatine will contract too much.

DEFECTS IN NEGATIVES.

A perfect negative presupposes a perfect plate, correct exposure, and correct development stopped at exactly the right time. It is almost unnecessary to say that all these conditions are rarely satisfied, and consequently most negatives fall more or less short of perfection. The defects may be broadly grouped under two heads, namely, those due to imperfections existing in the film before exposure, and those due to defects or errors in the way in which the plate has been treated. It will be more convenient to deal with the latter, and larger, group first, but there is really no hard and fast division between them.

THE NEGATIVE IS THIN, or in other words, whilst showing good gradation, and sufficient relative contrast between the different parts, is as a whole lacking in opacity or printing strength, and gives prints that are deficient in vigour and contrasts. The plate has been removed from the developer too soon, and the remedy is to intensify the image (see p. 51). Sometimes the want of opacity is due to the fact that the developer was too cold.


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